This invention relates to the field of laminated polymer films and, more particularly, to such films provided with coatings intended to impart special properties thereto such as sealability, machinability, and the like, making the films especially suitable for packaging applications.
U.S. Pat. No. 3,753,769 describes an acrylic based terpolymer coating composition, adapted for use in coating polyolefin films, comprising an interpolymer of (a) from about 2 to about 15 parts by weight of an alpha-beta monoethylenically unsaturated carboxylic acid and (b) from about 85 to about 98 parts by weight of neutral monomer esters comprising an alkyl acrylate ester and an alkyl methacrylate ester. When applied to a suitable substrate film, e.g., oriented polypropylene, the foregoing coating composition confers hitherto unavailable properties on the film such as improving its heat seal properties while simultaneously improving its blocking characteristics, hot slip properties, stiffness, and optical properties. There is, however, no suggestion in U.S. Pat. No. 3,753,769 of applying the coating composition to a laminate.
U.S. Pat. Nos. 4,125,662; 4,230,767; 4,235,365; 4,275,119; 4,275,120; 4,291,092; 4,297,411; 4,439,493; and, 4,447,494 each discloses a polymer structure including a base layer of oriented polypropylene and a surface, or skin, layer of an olefin copolymer, e.g., ethylene-propylene copolymer, in some cases blended with another olefin resin. There is no hint in these disclosures, however, of applying a coating composition such as described in U.S. Pat. No. 3,753,769, supra, to such structures.